Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
1999-11-30
2001-08-28
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169300, C345S055000, C345S076000
Reexamination Certificate
active
06281633
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a driving apparatus for a plasma display panel, and more particularly to a plasma display panel driving apparatus that is capable of reducing the number of optical conductive devices.
2. Description of the Related Art
Generally, a plasma display panel (PDP) radiates a fluorescent body by an ultraviolet with a wavelength of 147 nm generated during a discharge of HE+Xe gas to thereby display a picture including characters and graphics. Such a PDP is easy to be made into a thin-film and large-dimension type. Moreover, the PDP provides a very improved picture quality owing to a recent technical development. The PDP is largely classified into a direct current (DC) driving system and an alternating current (AC) driving system.
The PDP of AC driving system is expected to be highlighted into a future display device because it has advantages in the low voltage drive and a prolonged life in comparison to the PDP of DC driving system. Also, the PDP of alternating current driving system allows an alternating voltage signal to be applied between electrodes having dielectric layer therebetween to generate a discharge every half-period of the signal, thereby displaying a picture. The AC-type PDP makes a memory effect because it uses a dielectric material into the surface of which a wall charge is accumulated during the discharge.
Referring to FIG.
1
and
FIG. 2
, the AC-type PDP includes a front substrate
1
provided with sustaining electrodes
10
, and a rear substrate
2
provided with address electrodes
4
. The front substrate
1
and the rear substrate
2
are spaced, in parallel to each other, with having a barrier rib
3
therebetween. A mixture gas such as Ne—Xe or He—Xe, etc. is injected into a discharge space defined by the front substrate
1
and the rear substrate
2
and the barrier rib
3
. These sustaining electrodes
10
make a pair by two within a single plasma discharge channel. One of a pair of sustaining electrodes
10
is used as a scanning/sustaining electrode that responds to a scanning pulse applied in the address interval to cause an opposite discharge along with the address electrodes
4
, and responds to a sustaining pulse applied in the sustaining interval to cause a surface discharge along with the adjacent sustaining electrodes
10
. Also, the sustaining electrodes
10
adjacent to the sustaining electrode
10
used as the scanning/sustaining electrode
10
used as a common sustaining electrode to which a sustaining pulse is applied commonly. On a front substrate
1
provided with the sustaining electrodes
10
, a dielectric layer
8
and a protective layer
9
are disposed. The dielectric layer
8
and a responsible for limiting a plasma discharge current as well as accumulating a wall charge during the discharge. The protective film
9
prevents a damage of the dielectric layer
8
caused by a sputtering generated during the plasma discharge and improves an emission efficiency of secondary electrons. This protective film is usually made from MgO. Barrier ribs
3
for dividing the discharge space is extended perpendicularly at the rear substrate
2
. On the surfaces of the rear substrate
2
and the barrier ribs
3
, there is provided a fluorescent layer
5
excited by a vacuum ultraviolet lay to generate a visible light.
As shown in
FIG. 3
, the PDP
20
has m×n discharge pixel cells
11
arranged in a matrix pattern. At each of the discharge pixel cells
11
, scanning/sustaining electrode lines Yl to Ym, hereinafter referred to as “Y electrode lines”, and common sustaining electrode lines Z
1
to Zm electrode lines Xl to Xn, hereinafter referred to as “electrode lines ” are crossed with respect to each other. The Y electrode lines Y
1
to Ym and the Z electrode lines Z
1
to Zm consist of the sustaining electrodes
10
making a pair. The X electrode lines X
1
to Xn consist of the address electrodes
4
.
FIG. 3
is a schematic view of a PDP driver shown in FIG.
1
. In
FIG. 3
, the PDP driver includes a scanning/sustaining driver
22
for driving the Y electrode lines Y
1
to Ym, a commons sustaining driver
24
for driving the Z electrode lines Z
1
to Zm, and first and second address drivers
26
A and
26
B for driving the X electrode lines X
1
to Xn. The scanning/sustaining driver
22
is connected to the Y electrode lines Y
1
to Ym to thereby select a scanning line to be displayed and generate a sustaining discharge at the selected scanning line. The common sustaining driver
24
is commonly connected to the Z electrode lines Z
1
to Zm to apply sustaining pulses with same waveform to all the Z electrode lines Z
1
to Zm, thereby causing the sustaining discharge. The first address driver
26
A supplies odd-numbered X electrode lines X
1
, X
3
, . . . , Xn-
3
, Xn-
1
with a video data, whereas the second address driver
26
B supplies even-numbered X electrode lines X
2
, X
4
, . . ., Xn-
2
, Xn with a video data.
In such a PDP, one frame consists of a number of sub-fields so as to realize gray levels by a combination of the sub-fields. For instance, when it is intended to realize 256 gray levels, one frame interval is time-divided into 8 sub-fields. Further, each of the 8 sub-fields is again divided into a reset interval, an address interval and a sustaining interval. In the reset interval, the entire field is initialized. In the address interval, the discharge pixel cells
11
to be displayed by a data are selected by the address discharge. The selected discharge pixel cells
11
sustain the discharge in the sustaining interval. The sustaining interval is lengthened by an interval corresponding to 2
n
depending on a weighting value of each sub-field. In other words, the sustaining interval involved in each of first to eight sub-fields is lengthened at a ratio of 2
0
, 2
1
, 2
3
, 2
4
, 2
5
, 2
6
and 2
7
. To this end, the number of sustaining pulses generated in the sustaining interval also increases into 2
0
, 2
1
, 2
3
, 2
4
, 2
5
, 2
6
and 2
7
depending on the sub-fields . The brightness and the chrominance of a displayed image are determined in accordance with a combination of the sub-fields.
A method of driving a PDP is largely classified into an address display separated (ADS) system in which the entire field is divided into an address interval and a sustaining interval, and an address while sustaining (AWS) system in which one field is divided into a number of blocks and an address interval and a sustaining interval coexist within one field.
FIG. 4
is a block diagram showing the configuration of a PDP driving apparatus of ADS system emphasized on the scanning/sustaining driver. In
FIG. 4
, the PDP driving apparatus of ADS system includes a PDP
20
having 480 Y electrode lines Y
1
to Y
480
, a scanning/sustaining driver
30
for driving the Y electrode lines Y
1
to Y
480
sequentially, photo-couplers
32
A to
32
D for transmitting a control data Cdata generated from a microcomputer
34
and common control signals CC
1
to CC
3
to the sustaining driver
30
, and first and second waveform generators
36
A and
36
B for applying a scanning pulse and a sustaining pulse to the sustaining driver
30
. The sustaining driver
30
consists of first to eighth driver integrated circuits (ICs)
30
A to
30
H to the first photo-coupler
32
A in cascade. Each of the driver ICs
30
A to
30
H responds to the control data Cdata from the first photo-coupler
32
A to driver
60
Y electrode lines sequentially. In other words, the driver ICs
30
A to
30
H respond to the control data Cdata to be sequentially driven, thereby applying a scanning pulse to the first Y electrode line Yl to the 480th Y electrode line Y
480
sequentially in the address interval. The driver ICs
30
A to
30
H respond to the common control signals CC
1
to CC
3
at the moment of transiting from the address interval into the sustaining interval to drop voltages at the
480
Y electrodes Y
1
to Y
480
simultaneously into a ground level, and thereafter apply a sustaining pulse to the Y
Kang Seong Ho
Lee Eung Kwan
Fleshner & Kim LLP
LG Electronics Inc.
Vu David
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